I have a Hayward H-Series draft induced spa heaster, 100K BTUs, natural gas model H100ID1. The heat exchanger failed. The heater is 7 years old. Should I replace the heat exchanger and thermostat myself to the tune of around $500, or replace the whole heater for about $1000?
I do have one other odd option. The failure point is where the thermostat enters the heat exchanger pipe. It is a dry well normally. However, water now shoots out of it. I could seal the thermostat bulb into the hole using some kind of permanent putty, and the heat exchanger will continue to work, though not sure for how long. I might get 1 or two more years out of it, or I might get 5 days. It wouldn't cost me hardly anything to try, and since the heat exchanger is already shot, I have nothing to lose (if I replace the whole unit -- I could lose the thermostat). I was going to use this super epoxy plumbing putty that hardens into a metal like material which a plumber recommended to me. Also, I don't know what will fail first, the heat exchanger or the putty. If the putty fails, I risk water leaving the system and the pump running dry -- 7 year old nosy 2 speed pump which leaks water and probably also about to fail.
Another thought, similar to the above: Partially fill the dry well with the putty, or something, since the new thermostat is smaller, and then just clip the thermostat to the heat exchanger (as the instructions state). That might close it up and the thermostat would stay dry. What would I fill it with?
Anyway, any thoughts?
Link to the spa heater manual: